1. Field of the Invention
This invention relates to a system for the production of hydrocarbons at sea, by employing a moored production vessel or ship, whereby the ship concerned is equipped with mooring means preferably at its bow part, and at least one connection unit for a production riser from the seabed, and where there is involved anchor means disposed at the seabed, as well as at least one anchoring line adapted to connect the anchor means to the mooring means on the ship.
2. Description of the Related Art
In offshore oil and gas activity there is often the question of very important operations that can be difficult under certain conditions, and whereby there is usually involved transfer of fluids. Fluids in the form of hydrocarbons are of particular interest in this connection, since the invention is directed to a production system for oil or gas wells at the seabed. In such a system the anchoring function is a very important part of the total arrangement. Under varying and difficult conditions, whereby wind, waves and ocean currents have influence, great stresses and forces can occur during such mooring and carrying out of these operations. Such stresses in the first place can lead to wrecking and for example uncontrolled oil discharge.
In two international patent applications filed simultaneously, focus is placed on a pure mooring system, i.e. international application no. PCT/NO96/00203 (our ref. INT6165L), and a loading-unloading system respectively, i.e. international patent application no. PCT/NO96/00202 (our ref. INT6252L). Thus the present invention has several points of contact with the contents of these two simultaneous patent applications. When comparing with the latter of the two applications, it is to be remarked in particular that in production the seabed there will normally occur much higher pressures in the fluids concerned, than what will be found during usual loading or unloading of hydrocarbons for example.